The research proposed is a continuation of single unit studies in the visual system of Decapod Crustacea. They will concern both a closer study of those classes of visual interneurones so far found in different species and studies of the significance of the different classes in the behavior of the animals. Instrumentation is also planned for a closer study of the properties of "seeing" visual fibers in order to obtain more precise spatial and temporal relationships between their activation and various optically evoked behavioral reactions.